text stringlengths 105 4.57k | label int64 0 1 | label_text stringclasses 2
values |
|---|---|---|
* In Thomson scattering light interacts with electrons (this is the low-energy limit of Compton scattering).
* In Rayleigh scattering a medium composed of particles whose sizes are much smaller than the wavelength scatters light sideways. In this scattering process, the energy (and therefore the wavelength) of the incident light is conserved and only its direction is changed. In this case, the scattering intensity is inversely proportional to the fourth power of the reciprocal wavelength of the light. | 0 | Theoretical and Fundamental Chemistry |
In human digestion, proteins in food are broken down into smaller peptide chains by digestive enzymes such as pepsin, trypsin, chymotrypsin, and elastase, and into amino acids by various enzymes such as carboxypeptidase, aminopeptidase, and dipeptidase. It is necessary to break down proteins into small peptides (tripeptides and dipeptides) and amino acids so they can be absorbed by the intestines, and the absorbed tripeptides and dipeptides are also further broken into amino acids intracellularly before they enter the bloodstream. Different enzymes have different specificity for their substrate; trypsin, for example, cleaves the peptide bond after a positively charged residue (arginine and lysine); chymotrypsin cleaves the bond after an aromatic residue (phenylalanine, tyrosine, and tryptophan); elastase cleaves the bond after a small non-polar residue such as alanine or glycine.
In order to prevent inappropriate or premature activation of the digestive enzymes (they may, for example, trigger pancreatic self-digestion causing pancreatitis), these enzymes are secreted as inactive zymogen. The precursor of pepsin, pepsinogen, is secreted by the stomach, and is activated only in the acidic environment found in stomach. The pancreas secretes the precursors of a number of proteases such as trypsin and chymotrypsin. The zymogen of trypsin is trypsinogen, which is activated by a very specific protease, enterokinase, secreted by the mucosa of the duodenum. The trypsin, once activated, can also cleave other trypsinogens as well as the precursors of other proteases such as chymotrypsin and carboxypeptidase to activate them.
In bacteria, a similar strategy of employing an inactive zymogen or prezymogen is used. Subtilisin, which is produced by Bacillus subtilis, is produced as preprosubtilisin, and is released only if the signal peptide is cleaved and autocatalytic proteolytic activation has occurred. | 1 | Applied and Interdisciplinary Chemistry |
The Ornstein–Uhlenbeck process is a process defined as
with . Physically, this equation can be motivated as follows: a particle of mass with velocity moving in a medium, e.g., a fluid, will experience a friction force which resists motion whose magnitude can be approximated as being proportional to particles velocity with . Other particles in the medium will randomly kick the particle as they collide with it and this effect can be approximated by a white noise term; . Newtons second law is written as
Taking for simplicity and changing the notation as leads to the familiar form .
The corresponding Fokker–Planck equation is
The stationary solution () is | 1 | Applied and Interdisciplinary Chemistry |
Plastocyanin is one of the family of blue copper proteins that are involved in electron transfer reactions. The copper-binding site is described as distorted trigonal pyramidal. The trigonal plane of the pyramidal base is composed of two nitrogen atoms (N and N) from separate histidines and a sulfur (S) from a cysteine. Sulfur (S) from an axial methionine forms the apex. The distortion occurs in the bond lengths between the copper and sulfur ligands. The Cu−S contact is shorter (207 pm) than Cu−S (282 pm).
The elongated Cu−S bonding destabilizes the Cu(II) form and increases the redox potential of the protein. The blue color (597 nm peak absorption) is due to the Cu−S bond where S(pπ) to Cu(d−y</sub>) charge transfer occurs.
In the reduced form of plastocyanin, His-87 will become protonated with a pK of 4.4. Protonation prevents it acting as a ligand and the copper site geometry becomes trigonal planar. | 1 | Applied and Interdisciplinary Chemistry |
ATP can be generated by substrate-level phosphorylation in mitochondria in a pathway that is independent from the proton motive force. In the matrix there are three reactions capable of substrate-level phosphorylation, utilizing either phosphoenolpyruvate carboxykinase or succinate-CoA ligase, or monofunctional C1-tetrahydrofolate synthase. | 1 | Applied and Interdisciplinary Chemistry |
The bomb pulse is the sudden increase of carbon-14 (C) in the Earth's atmosphere due to the hundreds of aboveground nuclear bombs tests that started in 1945 and intensified after 1950 until 1963, when the Limited Test Ban Treaty was signed by the United States, the Soviet Union and the United Kingdom. These hundreds of blasts were followed by a doubling of the relative concentration of C in the atmosphere. The reason for the term “relative concentration”, is because the measurements of C levels by mass spectrometers are most accurately made by comparison to another carbon isotope, often the common isotope C. Isotope abundance ratios are not only more easily measured, they are what C carbon daters want, since it is the fraction of carbon in a sample that is C, not the absolute concentration, that is of interest in dating measurements. The figure shows how the fraction of carbon in the atmosphere that is C, of order only a part per trillion, has changed over the past several decades following the bomb tests. Because C concentration has increased by about 30% over the past fifty years, the fact that “pMC”, measuring the isotope ratio, has returned (almost) to its 1955 value, means that C concentration in the atmosphere remains some 30% higher than it once was. Carbon-14, the radioisotope of carbon, is naturally developed in trace amounts in the atmosphere and it can be detected in all living organisms. Carbon of all types is continually used to form the molecules of the cells of organisms. Doubling of the concentration of C in the atmosphere is reflected in the tissues and cells of all organisms that lived around the period of nuclear testing. This property has many applications in the fields of biology and forensics. | 0 | Theoretical and Fundamental Chemistry |
The R is the functional group attached to a tertiary carbon. If the functional group was an OH group, this compound would be commonly called tert-butanol or t-butanol. When a functional group is attached to a tertiary carbon, the prefix -tert (-t) is used in the common name for the compound. An example of this is shown in the figure. | 0 | Theoretical and Fundamental Chemistry |
In a living cell, ultrasensitive modules are embedded in a bigger network with upstream and downstream components. This components may constrain the range of inputs that the module will receive as well as the range of the module's outputs that network will be able to detect. Altszyler et al. (2014) studied how the effective ultrasensitivity of a modular system is affected by these restrictions. They found for some ultrasensitive motifs that dynamic range limitations imposed by downstream components can produce effective sensitivities much larger than that of the original module when considered in isolation. | 1 | Applied and Interdisciplinary Chemistry |
Although the sulfide content in sample can be determined straight forwardly as described for sulfites, the results are often poor and inaccurate. A better, alternative method with higher accuracy is available, which involves the addition of excess but known volume of standard sodium arsenite solution to the sample, during which arsenic trisulfide is precipitated:
The excess arsenic trioxide is then determined by titrating against standard iodine solution using starch indicator. Note that for the best results, the sulfide solution must be dilute with the sulfide concentration not greater than 0.01 M. | 0 | Theoretical and Fundamental Chemistry |
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, opacity, and luster, but may have properties that differ from those of the pure metals, such as increased strength or hardness. In some cases, an alloy may reduce the overall cost of the material while preserving important properties. In other cases, the mixture imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength.
In an alloy, the atoms are joined by metallic bonding rather than by covalent bonds typically found in chemical compounds. The alloy constituents are usually measured by mass percentage for practical applications, and in atomic fraction for basic science studies. Alloys are usually classified as substitutional or interstitial alloys, depending on the atomic arrangement that forms the alloy. They can be further classified as homogeneous (consisting of a single phase), or heterogeneous (consisting of two or more phases) or intermetallic. An alloy may be a solid solution of metal elements (a single phase, where all metallic grains (crystals) are of the same composition) or a mixture of metallic phases (two or more solutions, forming a microstructure of different crystals within the metal).
Examples of alloys include red gold (gold and copper), white gold (gold and silver), sterling silver (silver and copper), steel or silicon steel (iron with non-metallic carbon or silicon respectively), solder, brass, pewter, duralumin, bronze, and amalgams.
Alloys are used in a wide variety of applications, from the steel alloys, used in everything from buildings to automobiles to surgical tools, to exotic titanium alloys used in the aerospace industry, to beryllium-copper alloys for non-sparking tools. | 1 | Applied and Interdisciplinary Chemistry |
RNA-seq uses reverse transcriptase to convert the mRNA template to cDNA. During library preparation, the cDNA is fragmented into small pieces, which then serve as the template for sequencing. After sequencing RNA-seq analysis can then be performed. | 1 | Applied and Interdisciplinary Chemistry |
The inheritance pattern of genes existing in the cell organelles such as mitochondria which named cytoplasmic inheritance differs from nuclear genes pattern. | 1 | Applied and Interdisciplinary Chemistry |
In 1799, Davy became increasingly well known due to his experiments with the physiological action of some gases, including laughing gas (nitrous oxide). The gas was first synthesised in 1772 by the natural philosopher and chemist Joseph Priestley, who called it dephlogisticated nitrous air (see phlogiston). Priestley described his discovery in the book Experiments and Observations on Different Kinds of Air (1775), in which he described how to produce the preparation of "nitrous air diminished", by heating iron filings dampened with nitric acid. In another letter to Giddy, on 10 April, Davy informs him: "I made a discovery yesterday which proves how necessary it is to repeat experiments. The gaseous oxide of azote (the laughing gas) is perfectly respirable when pure. It is never deleterious but when it contains nitrous gas. I have found a mode of making it pure." He said that he breathed sixteen quarts of it for nearly seven minutes, and that it "absolutely intoxicated me."
In addition to Davy himself, his enthusiastic experimental subjects included his poet friends Robert Southey and Samuel Taylor Coleridge, as well as Gregory Watt and James Watt, other close friends. James Watt built a portable gas chamber to facilitate Davys experiments with the inhalation of nitrous oxide. At one point the gas was combined with wine to judge its efficacy as a cure for hangover (his laboratory notebook indicated success). The gas was popular among Davys friends and acquaintances, and he noted that it might be useful for performing surgical operations. Anesthetics were not regularly used in medicine or dentistry until decades after Davy's death. | 1 | Applied and Interdisciplinary Chemistry |
Following a major forgery of Australias newly introduced $10 notes in 1967, Solomon was invited to a meeting about how to make more secure bank notes. Given his background in polymer science Solomons idea was to print the notes on a plastic substrate rather than the traditional paper, and incorporate optically variable devices – defined as a device that changes its appearance when something external is done to the note.
Solomon went on to lead the research team and was the principal inventor of the worlds first polymer banknote, with the first note issued into circulation in 1988: the Australian bicentennial $10. He has chronicled the history of the development of polymer banknotes in The Plastic Banknote: From Concept to Reality', co-authored with Tom Spurling (published in 2014). | 0 | Theoretical and Fundamental Chemistry |
Birchall married Pauline Mary Jones at Sheffield register office on 2 June 1956. They had two sons, Shaun and Timothy.
James Derek Birchall died in a traffic accident. He was “struck by a vehicle on a pedestrian crossing in London on 30 November 1995. After several days on a life-support machine he died without regaining consciousness on 7 December.” He was buried at St John the Evangelist's Church, Norley, alongside his wife, who had died five years earlier. | 0 | Theoretical and Fundamental Chemistry |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), and Valine (Val, V). | 1 | Applied and Interdisciplinary Chemistry |
Delivery of DDRNAI DNA constructs is simplified by the existence of several clinically approved and well-characterized gene therapy vectors developed for the purpose. Delivery is a major challenge for RNAi-based therapeutics with new modifications and reagents continually being developed to optimize target cell delivery. Two broad strategies to facilitate the delivery of DNA constructs to the desired cells are available: these use either viral vectors or one of several classes of transfection reagents.
In vivo delivery of DDRNAI constructs has been demonstrated using a range of vectors and reagents with different routes of administration (ROA).
DDRNAI constructs have also been successfully delivered into host cells ex vivo, and then transplanted back into the host.
For example, in phase I clinical trial at the City of Hope National Medical Center, California, US, four HIV-positive patients with non-Hodgkin's lymphoma were successfully treated with autologous hematopoietic progenitor cells pre-transduced ex vivo with DDRNAI constructs using lentiviral vectors. This construct was designed to express three therapeutic RNAs, one of which was a shRNA, thereby combating HIV replication in three different ways:
*shRNA, that silences the tat and rev genes of the HIV genome
*CCR5 ribozyme, inhibiting viral cell entry
*TAR decoy RNA, inhibiting initiation of viral transcription.
Ongoing expression of the shRNA has been confirmed in T cells, monocytes, and B cells more than one year after transplantation. | 1 | Applied and Interdisciplinary Chemistry |
A Mach wave propagates across the flow at the Mach angle μ, which is the angle formed between the Mach wave wavefront and a vector that points opposite to the vector of motion. It is given by
where M is the Mach number.
Mach waves can be used in schlieren or shadowgraph observations to determine the local Mach number of the flow. Early observations by Ernst Mach used grooves in the wall of a duct to produce Mach waves in a duct, which were then photographed by the schlieren method, to obtain data about the flow in nozzles and ducts. Mach angles may also occasionally be visualized out of their condensation in air, for example vapor cones around aircraft during transonic flight. | 1 | Applied and Interdisciplinary Chemistry |
There are currently a number of on-going efforts to solve the structures for every protein in a given proteome. | 1 | Applied and Interdisciplinary Chemistry |
Several methods are known to recover carbonyl compounds from N,N-dialkylhydrazones. Procedures include oxidative, hydrolytic or reductive cleavage conditions and can be compatible with a wide range of functional groups. | 0 | Theoretical and Fundamental Chemistry |
Atmospheric optics ray tracing codes - this article list codes for light scattering using ray-tracing technique to study atmospheric optics phenomena such as rainbows and halos. Such particles can be large raindrops or hexagonal ice crystals. Such codes are one of many approaches to calculations of light scattering by particles. | 0 | Theoretical and Fundamental Chemistry |
Thermal physics is the combined study of thermodynamics, statistical mechanics, and kinetic theory of gases. This umbrella-subject is typically designed for physics students and functions to provide a general introduction to each of three core heat-related subjects. Other authors, however, define thermal physics loosely as a summation of only thermodynamics and statistical mechanics.
Thermal physics can be seen as the study of system with larger number of atom, it unites thermodynamics to statistical mechanics. | 0 | Theoretical and Fundamental Chemistry |
The Second World War forced the company to relocate from Paris to Vichy, where several other pharmaceutical companies were already installed. The Vichy Regime took an interest in the company, and attempted to despoil Jewish stakeholders. However, two of the main stakeholders were from Switzerland, and Swiss ambassador Walter Stucki managed to first delay the ploy, and eventually to derail it entirely.
Business slowed down for Tho-Radia during the war, but from 1948 it gathered momentum again, as Alexis Moussalli and chemist Pierre Corniou developed further products such as skincare beauty milk, perfume and lipstick. At its zenith, the company had between 80 and 90 employees. | 0 | Theoretical and Fundamental Chemistry |
Ficks laws of diffusion describe diffusion and were first posited by Adolf Fick in 1855 on the basis of largely experimental results. They can be used to solve for the diffusion coefficient, . Ficks first law can be used to derive his second law which in turn is identical to the diffusion equation.
Ficks first law: Movement of particles from high to low concentration (diffusive flux) is directly proportional to the particles concentration gradient.
Ficks second law': Prediction of change in concentration gradient with time due to diffusion.
A diffusion process that obeys Fick's laws is called normal or Fickian diffusion; otherwise, it is called anomalous diffusion or non-Fickian diffusion. | 0 | Theoretical and Fundamental Chemistry |
In their modeling, Watson and Crick restricted themselves to what they saw as chemically and biologically reasonable. Still, the breadth of possibilities was very wide. A breakthrough occurred in 1952, when Erwin Chargaff visited Cambridge and inspired Crick with a description of experiments Chargaff had published in 1947. Chargaff had observed that the proportions of the four nucleotides vary between one DNA sample and the next, but that for particular pairs of nucleotides—adenine and thymine, guanine and cytosine—the two nucleotides are always present in equal proportions.
Using X-ray diffraction, as well as other data from Rosalind Franklin and her information that the bases were paired, James Watson and Francis Crick arrived at the first accurate model of DNAs molecular structure in 1953, which was accepted through inspection by Rosalind Franklin. The discovery was announced on February 28, 1953; the first Watson/Crick paper appeared in Nature on April 25, 1953. Sir Lawrence Bragg, the director of the Cavendish Laboratory, where Watson and Crick worked, gave a talk at Guys Hospital Medical School in London on Thursday, May 14, 1953, which resulted in an article by Ritchie Calder in the News Chronicle of London, on Friday, May 15, 1953, entitled "Why You Are You. Nearer Secret of Life." The news reached readers of The New York Times the next day; Victor K. McElheny, in researching his biography, "Watson and DNA: Making a Scientific Revolution", found a clipping of a six-paragraph New York Times article written from London and dated May 16, 1953, with the headline "Form of Life Unit in Cell Is Scanned." The article ran in an early edition and was then pulled to make space for news deemed more important. (The New York Times subsequently ran a longer article on June 12, 1953). The Cambridge University undergraduate newspaper also ran its own short article on the discovery on Saturday, May 30, 1953. Bragg's original announcement at a Solvay Conference on proteins in Belgium on April 8, 1953, went unreported by the press. In 1962 Watson, Crick, and Maurice Wilkins jointly received the Nobel Prize in Physiology or Medicine for their determination of the structure of DNA. | 1 | Applied and Interdisciplinary Chemistry |
Due to redox-disequilibrium, selenium could be very reluctant to abiotic chemical reduction and would be released from the waste (spent fuel or vitrified waste) as selenate (), a soluble Se(VI) species, not sorbed onto clay minerals. Without solubility limit and retardation for aqueous selenium, the dose of Se is comparable to that of I. Moreover, selenium is an essential micronutrient as it is present in the catalytic centers in the glutathione peroxidase, an enzyme needed by many organisms for the protection of their cell membrane against oxidative stress damages; therefore, radioactive Se can be easily bioconcentrated in the food web. In the presence of nitrate () released in deep geological clay formations by bituminized waste issued from the spent fuel dissolution step during their reprocessing, even reduced forms of selenium could be easily oxidised and mobilised. | 0 | Theoretical and Fundamental Chemistry |
David Phillips, (born 3 December 1939) is a British chemist specialising in photochemistry and lasers, and was president of the Royal Society of Chemistry from 2010 to 2012. | 0 | Theoretical and Fundamental Chemistry |
The time that a particle of fluid has been in a control volume (e.g. a reservoir) is known as its age. In general, each particle has a different age. The frequency of occurrence of the age in the set of all the particles that are located inside the control volume at time is quantified by means of the (internal) age distribution .
At the moment a particle leaves the control volume, its age is the total time that the particle has spent inside the control volume, which is known as its residence time. The frequency of occurrence of the age in the set of all the particles that are leaving the control volume at time is quantified by means of the residence time distribution, also known as exit age distribution .
Both distributions are assumed to be positive and to have unitary integral along the age:
In the case of steady flow, the distributions are assumed to be independent of time, that is , which may allow to redefine the distributions as simple functions of the age only.
If the flow is steady (but a generalization to non-steady flow is possible) and is conservative, then the exit age distribution and the internal age distribution can be related one to the other:
Distributions other than and can be usually traced back to them. For example, the fraction of particles leaving the control volume at time with an age greater or equal than is quantified by means of the washout function , that is the complementary to one of the cumulative exit age distribution: | 0 | Theoretical and Fundamental Chemistry |
Salimuzzaman was born in Subeha (Barabanki District) near Lucknow on 19 October 1897. His father's name was Chaudhry Muhammad Zaman and his elder brother Chaudhry Khaliquzzaman was a distinguished All India Muslim League leader and one of the founding fathers of Pakistan. He received his early education from Lucknow, both in the Urdu and Persian languages, and soon developed interest in literature, poetry, and calligraphy from his father Sheikh Muhammad Zaman. He graduated in Philosophy and Persian language, from Muhammadan Anglo-Oriental College (that would later become Aligarh Muslim University) in 1920.
In 1920, Siddiqui proceeded to University College London to study medicine. However, after one year of pre-medical studies, he moved to Frankfurt University in 1921 to study chemistry. In 1924, he married his German classmate, Ethel Wilhelmina Schneeman. He received Doctor of Philosophy under the supervision of Julius Von Braun in 1927. During his college days in Germany in the 1920s, Germany experienced high inflation and he went through some hard economic times. In these tough times, Indias then eminent philanthropist Hakim Ajmal Khan used to send him Rupees400 every month. Many years later, as a successful scientist in Pakistan, Siddiqui repaid Hakeem Ajmal Khans kindness by dedicating his discoveries to him.
On his return, he established the Ayurvedic and Unani Tibbi Research Institute at the Tibbia College Delhi, under the guidance of Hakim Ajmal Khan. He was appointed its first director. However, soon after the death of Hakim Ajmal Khan, Siddiqui left the post. In 1940, he joined Indian Council for Scientific and Industrial Research where he worked until 1951 when he migrated to Pakistan on the request of Prime Minister Liaquat Ali Khan. | 0 | Theoretical and Fundamental Chemistry |
K2.3 is found in the central nervous system (CNS), muscle, liver, pituitary, prostate, kidney, pancreas and vascular endothelium tissues. K2.3 is most abundant in regions of the brain, but has also been found to be expressed in significant levels in many other peripheral tissues, particularly those rich in smooth muscle, including the rectum, corpus cavernosum, colon, small intestine and myometrium.
The expression level of KCNN3 is dependent on hormonal regulation, particularly by the sex hormone estrogen. Estrogen not only enhances transcription of the KCNN3 gene, but also affects the activity of K2.3 channels on the cell membrane. In GABAergic preoptic area neurons, estrogen enhanced the ability of α1 adrenergic receptors to inhibit K2.3 activity, increasing cell excitability. Links between hormonal regulation of sex organ function and K2.3 expression have been established. The expression of K2.3 in the corpus cavernosum in patients undergoing estrogen treatment as part of gender reassignment surgery was found to be increased up to 5-fold. The influence of estrogen on K2.3 has also been established in the hypothalamus, uterine and skeletal muscle. | 1 | Applied and Interdisciplinary Chemistry |
In general, a sample is a limited quantity of something which is intended to be similar to and represent a larger amount of that thing(s). The things could be countable objects such as individual items available as units for sale, or an uncountable material. Even though the word "sample" implies a smaller quantity taken from a larger amount, sometimes full biological or mineralogical specimens are called samples if they are taken for analysis, testing, or investigation like other samples. They are also considered samples in the sense that even whole specimens are "samples" of the full population of many individual organisms. The act of obtaining a sample is called "sampling" and can be performed manually by a person or by automatic process. Samples of material can be taken or provided for testing, analysis, investigation, quality control, demonstration, or trial use. Sometimes, sampling may be performed continuously. | 0 | Theoretical and Fundamental Chemistry |
Energy accounting is a system used in energy management systems to measure and analyze energy consumption to improve energy efficiency within an organization. Organisations such as Intel corporation use these systems to track energy usage.
Various energy transformations are possible. An energy balance can be used to track energy through a system. This becomes a useful tool for determining resource use and environmental impacts. How much energy is needed at each point in a system is measured, as well as the form of that energy. An accounting system keeps track of energy in, energy out, and non-useful energy versus work done, and transformations within a system. Sometimes, non-useful work is what is often responsible for environmental problems. | 0 | Theoretical and Fundamental Chemistry |
In 1988, the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances introduced detailed provisions and requirements relating the control of precursors used to produce drugs of abuse.
In Europe the Regulation (EC) No. 273/2004 of the European Parliament and of the Council on drug precursors was adopted on 11 February 2004. (European law on drug precursors) | 1 | Applied and Interdisciplinary Chemistry |
Ultraviolet absorbers are molecules used in organic materials (polymers, paints, etc.) to absorb UV radiation to reduce the UV degradation (photo-oxidation) of a material. The absorbers can themselves degrade over time, so monitoring of absorber levels in weathered materials is necessary.
In sunscreen, ingredients that absorb UVA/UVB rays, such as avobenzone, oxybenzone and octyl methoxycinnamate, are organic chemical absorbers or "blockers". They are contrasted with inorganic absorbers/"blockers" of UV radiation such as carbon black, titanium dioxide, and zinc oxide.
For clothing, the ultraviolet protection factor (UPF) represents the ratio of sunburn-causing UV without and with the protection of the fabric, similar to sun protection factor (SPF) ratings for sunscreen. Standard summer fabrics have UPFs around 6, which means that about 20% of UV will pass through.
Suspended nanoparticles in stained-glass prevent UV rays from causing chemical reactions that change image colors. A set of stained-glass color-reference chips is planned to be used to calibrate the color cameras for the 2019 ESA Mars rover mission, since they will remain unfaded by the high level of UV present at the surface of Mars.
Common soda–lime glass, such as window glass, is partially transparent to UVA, but is opaque to shorter wavelengths, passing about 90% of the light above 350 nm, but blocking over 90% of the light below 300 nm. A study found that car windows allow 3–4% of ambient UV to pass through, especially if the UV was greater than 380 nm. Other types of car windows can reduce transmission of UV that is greater than 335 nm. Fused quartz, depending on quality, can be transparent even to vacuum UV wavelengths. Crystalline quartz and some crystals such as CaF and MgF transmit well down to 150 nm or 160 nm wavelengths.
Wood's glass is a deep violet-blue barium-sodium silicate glass with about 9% nickel oxide developed during World War I to block visible light for covert communications. It allows both infrared daylight and ultraviolet night-time communications by being transparent between 320 nm and 400 nm and also the longer infrared and just-barely-visible red wavelengths. Its maximum UV transmission is at 365 nm, one of the wavelengths of mercury lamps. | 0 | Theoretical and Fundamental Chemistry |
The EBF intends to stimulate further harmonization of industry practices in bioanalysis, to bring a common understanding of the interpretation of regulatory issues and more clarity to the implementation of procedures in order to achieve best practices in the world of bioanalysis. The forum currently hosts two types of meetings: | 0 | Theoretical and Fundamental Chemistry |
In many modern studies, the Polanyi theory is widely used in the study of activated carbons, or carbon black. The theory has been successfully used to model a variety of scenarios such as the gas adsorption on activated carbon and the adsorption process of nonionic polycyclic aromatic hydrocarbons. Later on, experiments also showed that it can model ionic polycyclic aromatic hydrocarbons such as phenols and anilines. More recently, the Polyani adsorption isotherm has been used to model to adsorption of carbon nanoparticles. | 0 | Theoretical and Fundamental Chemistry |
In principle, any technologies used for metabolomics can be used for exometabolomics. However, liquid chromatography–mass spectrometry (LC–MS) has been the most widely used. As with typical metabolomic measurements, metabolites are identified based on accurate mass, retention time, and their MS/MS fragmentation patterns, in comparison to authentic standards. Chromatographies typically used are hydrophilic interaction liquid chromatography for the measurement of polar metabolites, or reversed-phase (C18) chromatography for the measurement of non-polar compounds, lipids, and secondary metabolites. Gas chromatography–mass spectrometry can also be used to measure sugars and other carbohydrates, and to obtain complete metabolic profiles.
Because LC–MS does not give spatial data on metabolite localization, it can be complemented with mass spectrometry imaging (MSI). | 1 | Applied and Interdisciplinary Chemistry |
Adjuvants are materials added to improve immunogenicity of recombinant subunit vaccines.
Adjuvants increase the magnitude of adaptive response to the vaccine and guide the activation of the most effective forms of immunity for each specific pathogen (e.g. increasing generation of T cell memory). Addition of adjuvants may confer benefits including dose sparing and stabilisation of final vaccine formulation.
Appropriate adjuvants are chosen based on safety, tolerance, compatibility of antigen and manufacturing considerations. Commonly used adjuvants for recombinant subunit vaccines are Alum adjuvants (e.g. aluminium hydroxide), Emulsions (e.g. MF59) and Liposomes combined with immunostimulatory molecules (e.g. AS01). | 1 | Applied and Interdisciplinary Chemistry |
He was born in Göttingen on 2 August 1776 the eldest son of Dr Ernerst Johann Friedrich Stromeyer, professor of medicine at Göttingen University, and his wife, Marie Magdalena Johanne von Blum.
Stromeyer studied Chemistry and Medicine at Göttingen and Paris and received an MD degree from the University of Göttingen in 1800, studying under Johann Friedrich Gmelin and Louis Nicolas Vauquelin. He was then a professor at the university, and also served as an inspector of apothecaries. His students included Robert Bunsen.
In 1817, whilst studying compounds of zinc carbonate, Stromeyer discovered the element cadmium. Cadmium is a common impurity of zinc compounds, though often found only in minute quantities. He was also the first to recommend starch as a reagent for free iodine and he studied chemistry of arsine and bismuthate salts.
In 1819 he was the first scientist to describe the mineral eudialyte.
In 1826 he was elected a Fellow of the Royal Society of Edinburgh his proposer being Edward Turner. As his fellowship was Ordinary (rather than Foreign or Honorary) this means he was physically present in Edinburgh at that time. The following year he was elected a Foreign Fellow of the Royal Society of London.
In 1832 the mineral stromeyerite was named in his honour by mineralogist François Sulpice Beudant.
He died in Göttingen on 18 August 1835 aged 59. | 1 | Applied and Interdisciplinary Chemistry |
Fast neutron reactors use fast fission to produce energy, unlike most nuclear reactors. In a conventional reactor, a moderator is needed to slow down the neutrons so that they are more likely to fission atoms. A fast neutron reactor uses fast neutrons, so it does not use a moderator. Moderators may absorb a lot of neutrons in a thermal reactor, and fast fission produces a higher average number of neutrons per fission, so fast reactors have better neutron economy making a plutonium breeder reactor possible. However, a fast neutron reactor must use relatively highly enriched uranium or plutonium at the reactor startup so that the neutrons have a better chance of fissioning atoms. | 0 | Theoretical and Fundamental Chemistry |
Historians have not been able to determine when exactly the pharmacy opened, but the oldest records available show that the Raeapteek was already on its third owner in 1422. Some scholars consider the opening year to be 1415.
In a town council's notebook, there is an entry by a chemist named Nuclawes who stated that the owners of the pharmacy are 10 honourable men, the majority of whom are aldermen. Other documents dated after 1422 refer that the first chemist here was Johann Molner and that medicines were already being sold at the pharmacy in the second half of the 15th century. | 1 | Applied and Interdisciplinary Chemistry |
Convection-cooling is sometimes loosely assumed to be described by Newton's law of cooling.
Newtons law states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and its surroundings while under the effects of a breeze'. The constant of proportionality is the heat transfer coefficient. The law applies when the coefficient is independent, or relatively independent, of the temperature difference between object and environment.
In classical natural convective heat transfer, the heat transfer coefficient is dependent on the temperature. However, Newton's law does approximate reality when the temperature changes are relatively small, and for forced air and pumped liquid cooling, where the fluid velocity does not rise with increasing temperature difference. | 0 | Theoretical and Fundamental Chemistry |
Various inputs into this pathway have been identified. Activators include ligands of a number of receptors. Because certain signal transduction pathways oppose the STAT3-Ser/Hes3 signaling axis, blockers (inhibitors) of these signal transduction pathways promote the STAT3-Ser/Hes3 signaling axis and, therefore, also act as activators:
:* A non-canonical branch of the notch signaling pathway (activated by soluble forms of the notch ligands Delta4 and Jagged1). This has been shown in vitro and in vivo.
:* Activation of the Tie2 receptor by the ligand Angiopoietin 2. This has been shown in vitro and in vivo.
:* Activation of the insulin receptor by insulin. This has been shown in vitro and in vivo.
:* Treatment with an inhibitor of the Janus kinase (JAK). This has been shown in vitro.
:* Treatment with an inhibitor of the p38 MAP kinase kinase. This has been shown in vitro.
:* Treatment with cholera toxin. This has been shown in vitro. This particular treatment may bypass the STAT3-Ser stage and act more specifically at the level of Hes3 because it has a powerful effect on inducing the nuclear translocation of Hes3. | 1 | Applied and Interdisciplinary Chemistry |
Aso and Tagami were the first to report the polymerization of o-phthalaldehyde in 1967 using the cationic living polymerization technique. This technique, which was initially thought to require the usage of a strong Brönsted acid to initiate polymerization in addition to a strong nucleophile to depress polymerization and endcap the polymer chain was proven successful in a number of polymerization processes reported earlier. Interestingly, the authors were able to produce this polymer without using an initiator nor a terminator and determined the polymer's structure to be cyclic. In fact, they worked at liquid nitrogen temperature and relied on Boron trifluoride etherate catalyst which was sufficient to produce a polymer stable enough at room temperature for a few days. | 0 | Theoretical and Fundamental Chemistry |
Nesfatin/NUCB2 is expressed in the appetite-control hypothalamic nuclei such as paraventricular nucleus (PVN), arcuate nucleus (ARC), supraoptic nucleus (SON) of hypothalamus, lateral hypothalamic area (LHA), and zona incerta in rats. Nesfatin-1 immunoreactivity was also found in the brainstem nuclei such as nucleus of the solitary tract (NTS) and Dorsal nucleus of vagus nerve. | 1 | Applied and Interdisciplinary Chemistry |
The Jacobi elliptic function cn can be expanded into a Fourier series
(m) is known as the imaginary quarter period, while K(m) is also called the real quarter period of the Jacobi elliptic function. They are related through: (m) = K(1−m)
Since the interest here is in small wave height, corresponding with small parameter m ≪ 1, it is convenient to consider the Maclaurin series for the relevant parameters, to start with the complete elliptic integrals K and E:
Then the hyperbolic-cosine terms, appearing in the Fourier series, can be expanded for small m ≪ 1 as follows:
: with the nome q given by
The nome q has the following behaviour for small m:
Consequently, the amplitudes of the first terms in the Fourier series are:
So, for m ≪ 1 the Jacobi elliptic function has the first Fourier series terms:
The free surface η(x,t) of the cnoidal wave will be expressed in its Fourier series, for small values of the elliptic parameter m. First, note that the argument of the cn function is ξ/Δ, and that the wavelength λ = 2 Δ K(m), so:
Further, the mean free-surface elevation is zero. Therefore, the surface elevation of small amplitude waves is
Also the wavelength λ can be expanded into a Maclaurin series of the elliptic parameter m, differently for the KdV and the BBM equation, but this is not necessary for the present purpose.
For infinitesimal wave height, in the limit m → 0, the free-surface elevation becomes:
: with
So the wave amplitude is H, half the wave height. This is of the same form as studied in Airy wave theory, but note that cnoidal wave theory is only valid for long waves with their wavelength much longer than the average water depth. | 1 | Applied and Interdisciplinary Chemistry |
Sir Christopher Kelk Ingold (28 October 1893 – 8 December 1970) was a British chemist based in Leeds and London. His groundbreaking work in the 1920s and 1930s on reaction mechanisms and the electronic structure of organic compounds was responsible for the introduction into mainstream chemistry of concepts such as nucleophile, electrophile, inductive and resonance effects, and such descriptors as S1, S2, E1, and E2. He also was a co-author of the Cahn–Ingold–Prelog priority rules. Ingold is regarded as one of the chief pioneers of physical organic chemistry. | 0 | Theoretical and Fundamental Chemistry |
Foamed biopolymers have multiple purported applications in the biomedical and pharmaceuticals industry due to their modified surface properties. Gelatine films with curcumin dropped upon the surface, for instance, displayed a higher tolerance for ablation following its foaming; this tolerance is suspected to arise from curcumin's binding to proteins to protect from free radicals, as well as its anti-oxidant properties. These findings present implications for greater cellular surgery, as well as the manufacturing of biopolymers as a whole, due to these modifications from plasma irradiation. | 0 | Theoretical and Fundamental Chemistry |
Ordinarily, carbon dioxide is fixed to ribulose 1,5-bisphosphate (RuBP) by the enzyme RuBisCO in mesophyll cells exposed directly to the air spaces inside the leaf. This exacerbates the transpiration problem for two reasons: first, RuBisCo has a relatively low affinity for carbon dioxide, and second, it fixes oxygen to RuBP, wasting energy and carbon in a process called photorespiration. For both of these reasons, RuBisCo needs high carbon dioxide concentrations, which means wide stomatal apertures and, as a consequence, high water loss.
Narrower stomatal apertures can be used in conjunction with an intermediary molecule with a high carbon dioxide affinity, phosphoenolpyruvate carboxylase (PEPcase). Retrieving the products of carbon fixation from PEPCase is an energy-intensive process, however. As a result, the PEPCase alternative is preferable only where water is limiting but light is plentiful, or where high temperatures increase the solubility of oxygen relative to that of carbon dioxide, magnifying RuBisCo's oxygenation problem. | 0 | Theoretical and Fundamental Chemistry |
There are four main experimental methods. For less commonly used methods, see Rossotti and Rossotti. In all cases the range can be extended by using the competition method. An example of the application of this method can be found in palladium(II) cyanide. | 0 | Theoretical and Fundamental Chemistry |
The pharmacophore model of PDE5 usually consists of one hydrogen bond acceptor, one hydrophobic aliphatic carbon chain and two aromatic rings. Small hydrophobic pocket and H-loop of PDE5 enzyme are important for binding affinity of PDE5 inhibitors. As well as positional and conformational changes are observed upon inhibitor binding in many cases.
The active site of PDE5 is located at a helical bundle domain at the center of C domain (catalytic domain). The substrate pocket is composed of four subsites: M site (metal-binding site), Q pocket (core pocket), H pocket (hydrophobic pocket) and L region (lid region) as demonstrated in [https://commons.wikimedia.org/wiki/File:Figure_3._PDE5_Domains.png figure 3]. The Q pocket accommodates the pyrazolopyrimidinone group of sildenafil. That suggest that other chemicals similar to guanidine groups of cGMP can also bind at this region. The amino acids residues, Gln817, Phe820, Val782 and Tyr612, are lined in the Q pocket, they are highly conserved in all PDEs. The amide moiety of the pyrazolopyrimidinone group forms a bidentate hydrogen bond with the ɣ-amide group of Gln817. 3D structure of sildenafil is demonstrated in [https://commons.wikimedia.org/wiki/File:3D.Sild.2.png figure 4]. | 1 | Applied and Interdisciplinary Chemistry |
Cold fission or cold nuclear fission is defined as involving fission events for which fission fragments have such low excitation energy that no neutrons or gammas are emitted.
Cold fission events have so low a probability of occurrence that it is necessary to use a high-flux nuclear reactor to study them.
According to research first published in 1981, the first observation of cold fission events was in experiments on fission induced by thermal neutrons of uranium 233, uranium 235, and plutonium 239 using the high-flux reactor at the Institut Laue-Langevin in Grenoble, France. Other experiments on cold fission were also done involving Cm and Cf. A unified approach of cluster decay, alpha decay and cold fission was developed by Dorin N. Poenaru et al. A phenomenological interpretation was proposed by Gönnenwein and Duarte et al.
The importance of cold fission phenomena lies in the fact that fragments reaching detectors have the same mass that they obtained at the "scission" configuration, just before the attractive but short-range nuclear force becomes null, and only Coulomb interaction acts between fragments. After this, Coulomb potential energy is converted into fragments of kinetic energies, which—added to pre-scission kinetic energies—is measured by detectors.
The fact that cold fission preserves nuclear mass until the fission fragments reach the detectors permits the experimenter to better determine the fission dynamics, especially the aspects related to Coulomb and shell effects in low energy fission and nucleon pair breaking. Adopting several theoretical assumptions about scission configuration one can calculate the maximal value of kinetic energy as a function of charge and mass of fragments and compare them to experimental results. | 0 | Theoretical and Fundamental Chemistry |
It has been suggested that SOCS can help prevent cytokine-mediated apoptosis in diabetes through negative regulation of pro-inflammatory cytokines secreted by immune cells, such as IFNγ, TNFα and IL-15. Improper functioning of one specific SOCS, SOCS3 may lead to type 2 diabetes, as it has been found that SOCS3 plays an important role in proper leptin signaling. | 1 | Applied and Interdisciplinary Chemistry |
Epitaxially grown thin films of LAO can serve various purposes for correlated electrons heterostructures and devices. LAO is sometimes used as an epitaxial insulator between two conductive layers. Epitaxial LAO films can be grown by several methods, most commonly by pulsed laser deposition (PLD) and molecular beam epitaxy (MBE).
LAO-STO interfaces
The most important and common use for epitaxial LAO is at the lanthanum aluminate-strontium titanate interface. In 2004, it was discovered that when 4 or more unit cells of LAO are epitaxially grown on strontium titanate (SrTiO, STO), a conductive 2-dimensional layer is formed at their interface. Individually, LaAlO and SrTiO are non-magnetic insulators, yet LaAlO/SrTiO interfaces exhibit electrical conductivity, superconductivity,
ferromagnetism, large negative in-plane magnetoresistance, and giant persistent photoconductivity. The study of how these properties emerge at the LaAlO/SrTiO interface is a growing area of research in condensed matter physics. | 0 | Theoretical and Fundamental Chemistry |
In 2021, evidence for OH in the dayside atmosphere of the exoplanet WASP-33b was found in its emission spectrum at wavelengths between 1 and 2 micrometers. Evidence for OH in the atmosphere of exoplanet WASP-76b was subsequently found. Both WASP-33b and WASP-76b are ultra-hot Jupiters and it is likely that any water in their atmospheres is present as dissociated ions. | 0 | Theoretical and Fundamental Chemistry |
Photosynthesis is the only process that allows the conversion of atmospheric carbon (CO2) to organic (solid) carbon, and this process plays an essential role in climate models. This lead researchers to study the sun-induced chlorophyll fluorescence (i.e., chlorophyll fluorescence that uses the Sun as illumination source; the glow of a plant) as an indicator of photosynthetic efficiency of a region. This is interesting for scientists since its shows them things like the CO2 absorption of a forests, or the productivity of an agricultural region. The FLEX (satellite) is the upcoming satellite program by the European Space Agency designated to this type of measurements. | 0 | Theoretical and Fundamental Chemistry |
Gamma spectroscopy is the study of the energetic transitions in atomic nuclei, which are generally associated with the absorption or emission of gamma rays. As in optical spectroscopy (see Franck–Condon effect) the absorption of gamma rays by a nucleus is especially likely (i.e., peaks in a "resonance") when the energy of the gamma ray is the same as that of an energy transition in the nucleus. In the case of gamma rays, such a resonance is seen in the technique of Mössbauer spectroscopy. In the Mössbauer effect the narrow resonance absorption for nuclear gamma absorption can be successfully attained by physically immobilizing atomic nuclei in a crystal. The immobilization of nuclei at both ends of a gamma resonance interaction is required so that no gamma energy is lost to the kinetic energy of recoiling nuclei at either the emitting or absorbing end of a gamma transition. Such loss of energy causes gamma ray resonance absorption to fail. However, when emitted gamma rays carry essentially all of the energy of the atomic nuclear de-excitation that produces them, this energy is also sufficient to excite the same energy state in a second immobilized nucleus of the same type. | 0 | Theoretical and Fundamental Chemistry |
An optical variation of the single-fiber Wilhelmy method. Instead of measuring with a balance, the shape of the meniscus on the fiber is directly imaged using a high resolution camera. Automated meniscus shape fitting can then directly measure the static, advancing or receding contact angle on the fiber. | 0 | Theoretical and Fundamental Chemistry |
Singlet oxygen, systematically named dioxygen(singlet) and dioxidene, is a gaseous inorganic chemical with the formula O=O (also written as or ), which is in a quantum state where all electrons are spin paired. It is kinetically unstable at ambient temperature, but the rate of decay is slow.
The lowest excited state of the diatomic oxygen molecule is a singlet state.
It is a gas with physical properties differing only subtly from those of the more prevalent triplet ground state of O. In terms of its chemical reactivity, however, singlet oxygen is far more reactive toward organic compounds. It is responsible for the photodegradation of many materials but can be put to constructive use in preparative organic chemistry and photodynamic therapy. Trace amounts of singlet oxygen are found in the upper atmosphere and in polluted urban atmospheres where it contributes to the formation of lung-damaging nitrogen dioxide. It often appears and coexists confounded in environments that also generate ozone, such as pine forests with photodegradation of turpentine.
The terms singlet oxygen and triplet oxygen derive from each form's number of electron spins. The singlet has only one possible arrangement of electron spins with a total quantum spin of 0, while the triplet has three possible arrangements of electron spins with a total quantum spin of 1, corresponding to three degenerate states.
In spectroscopic notation, the lowest singlet and triplet forms of O are labeled Δ and Σ, respectively. | 0 | Theoretical and Fundamental Chemistry |
pH affects the reaction rate due to a variety of reasons. At a low pH, complexation of also occurs, leading to lower availability of to form reactive oxidative species (OH). Lower pH also results in the scavenging of OH by excess , hence reducing its reaction rate. Whereas at high pH, the reaction slows down due to precipitation of Fe(OH), lowering the concentration of the species in solution. Solubility of iron species is directly governed by the solution's pH. is about 100 times less soluble than in natural water at near-neutral pH, the ferric ion concentration is the limiting factor for the reaction rate. Under high pH conditions, the stability of the HO is also affected, resulting in its self-decomposition. Higher pH also decreased the redox potential of OH thereby reducing its effectiveness. pH plays a crucial role in the formation of free radicals and hence the reaction performance. Thus ongoing research has been done to optimize pH and amongst other parameters for greater reaction rates. | 1 | Applied and Interdisciplinary Chemistry |
The SQT approach has been praised for a variety of reasons as a technique for characterizing sediment conditions. Relative to the depth of information it provides, and the inclusive nature, it is very cost effective. It can be applied to all sediment classifications, and even adapted to soil and water column assessments (Chapman and McDonald 2005). A decision matrix can be employed such that all three measures be analyzed simultaneously, and a deduction of possible ecological impacts be made (USEPA 1994)
Other advantages of the SQT include information on the potential bioaccumulation and biomagnifcation effects of contaminants, and its flexibility in application, resulting from its design as a framework rather than a formula or standard method. By using multiple lines of evidence, there are a host of ways to manipulate and interpret SQT data (Bay and Weisberg 2012). It has been accepted on an international scale as the most comprehensive approach to assessing sediment (Chapman and McDonald 2005). The SQT approach to sediment testing has been used in North America, Europe, Australia, South America, and the Antarctic. | 1 | Applied and Interdisciplinary Chemistry |
Shelf-Break Fronts are a process by which stratification of the water column occurs. This stratification normally results in thermoclines, since they occur where a sudden change in water depth causes a constriction of the current flow. They can be expressed as a ratio of their potential energy due to maintaining mixed (non-stratified) conditions, to the dissipated energy produced by the current being forced across the sudden change in depth. This can be expressed as:
The energy terms can be expressed in very detailed equations, but with constant terms factored out, the important terms are water velocity (average velocity, ) and water depth (h).
The equation for the stratification index can be expressed as:
Where is a friction coefficient, approximated as 0.003 for a sandy bottom. This index can be calculated for any coastal region, usually in the range of +3 (highly stratified) to -2 (highly turbulent). | 0 | Theoretical and Fundamental Chemistry |
In terms of d-orbital splitting, ligand field theory (LFT) and crystal field theory (CFT) give similar results. CFT is an older, simpler model that treats ligands as point charges. LFT is more chemical, emphasizes covalent bonding and accommodates pi-bonding explicitly. | 0 | Theoretical and Fundamental Chemistry |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), Valine (Val, V) | 1 | Applied and Interdisciplinary Chemistry |
Predictive biomarkers measure the effect of a drug and tell if the drug is having its expected activity, but do not offer any direct information on the disease. Predictive biomarkers are highly sensitive and specific; therefore they increase diagnostic validity of a drug or toxin's site-specific effect by eliminating recall bias and subjectivity from those exposed. For example, when an individual is exposed to a drug or toxin, the concentration of that drug or toxin within the body, or the biological effective dose, provides a more accurate prediction for the effect of the drug or toxin compared to an estimation or measurement of the toxin from the origin or external environment. | 1 | Applied and Interdisciplinary Chemistry |
Dexlansoprazole ((R)-(+)-lansoprazole) has the same binding affinity to the proton pump as the (S)-enantiomer, but is associated with a three- to five-fold greater area under the plasma drug concentration time curve (AUC) compared with (S)-lansoprazole. With its dual release pharmaceutical formulation, the first quick release produces a plasma peak concentration about one hour after application, with a second delayed release producing another peak about four hours later. | 0 | Theoretical and Fundamental Chemistry |
The a/LCI system has recently been enhanced to allow operation in a clinical setting with the addition of a handheld wand. By carefully controlling the polarization in the delivery fiber, using polarization-maintaining fibers and inline polarizers, the new system allows manipulation of the handheld wand without signal degradation due to birefringence effects. In addition, the new system employed an anti-reflection coated ball lens in the probe tip, which reduces reflections that otherwise limit the depth range of the system.
The portable system uses a 2 ft by 2 ft optical breadboard as the base, with the source, fiber optic components, lens, beamsplitter, and imaging spectrometer mounted to the breadboard. An aluminum cover protects the optics. A fiber probe with a handheld probe enables easy access to tissue samples for testing. On the left side sits a white sample platform, where tissue is placed for testing. The handheld probe is used by the operator to select specific sites on the tissue from which a/LCI readings are acquired. | 0 | Theoretical and Fundamental Chemistry |
Joseph H. Burckhalter was a chemist who worked in the field of isothiocyanate compounds. In 1995 he was inducted into the National Inventors Hall of Fame. Burckhalter is also a member of the Medicinal Chemistry Hall of Fame.
Burckhalter earned a B.S. in chemistry from the University of South Carolina in 1934 and an M.S. in organic chemistry from the University of Illinois, Urbana, in 1938. In 1942, he received his doctorate in medicinal chemistry at the University of Michigan, where he had been a graduate student of Frederick Blicke. | 0 | Theoretical and Fundamental Chemistry |
In 2009, researchers developed siRNAs capable of targeting both polo-like kinase 1(PLK1) and kinesin spindle protein(KSP). Both proteins are important to the cell-cycle of tumor cells, PLK1 involved with phosphorylation of a variety of proteins and KSP integral to chromosome segregation during mitosis. Specifically, bipolar mitotic spindles are unable to form when KSP is inhibited, leading to arrest of the cell cycle and, eventually, apoptosis. Likewise, inhibition of PLK1 facilitates mitotic arrests and cell apoptosis. According to the study, a 2 mg/kg dose of PLK1-specific siRNA administered for 3 weeks to mice implanted with tumors resulted in increased survival times and obvious reduction of tumors. In fact, the median survival time of treated mice was 51 days as opposed to 32 days for the controls. Further, only 2 of the 6 mice treated had noticeable tumors around the implantation site. Even so, GAPDH, a tumor-derived signal, was present at low levels, indicating significant suppression of tumor growth but not complete elimination. Still, the results suggested minimal toxicity and no significant dysfunction of the bone marrow. Animals treated with KSP-specific siRNA, too, exhibited increased survival times of 28 days compared to 20 days in the controls. | 1 | Applied and Interdisciplinary Chemistry |
Search for a new anti-migraine drug started at Glaxo in 1972. Studies in the 1960s showed that vasoconstriction from 5-HT, ergotamine and noradrenaline could reduce migraine attacks. Research also showed that platelet 5-HT level is reduced during migraine. Because there are too many side-effects for 5-HT to be used as a drug, scientists started research on the receptors of 5-HT in order to discover and develop a more specific agonist for 5-HT receptors. Research on the 5-HT receptors and their effect led to discovery of several types and subtypes of 5-HT. AH24167 showed a vasodilation effect instead of vasoconstriction due to the agonist effect on another type of 5-HT receptors later assigned the name 5-HT. AH25086 was the second compound developed and showed a vasoconstriction effect but was not released as a drug due to low per oral bioavailability. Continued research led to the discovery of the first triptan drug, sumatriptan, that had both vasoconstriction effect, as well as better oral bioavailability. Sumatriptan was first launched in the Netherlands in 1991 and became available in the United States during 1993. | 1 | Applied and Interdisciplinary Chemistry |
Not only is PHY closely related to Substance P (SP), but it also has a higher affinity for the mammalian neurokinin receptors that Substance P can bind to. Researchers can make use of this behavior of PHY to study the behavior of smooth muscle - a tissue where NK1 can be found. Shiina et al. (2010) used PHY to show that tachykinins as a whole can cause the longitudinal contraction of smooth muscle tissue in esophageal tissue.
Singh et Maji made use of PHYs similarity to SP along with its sequence similarity to Amyloid B-peptide 25-35 [AB(25-35)]. Despite its sequence similarity to SP, Singh et Maji showed that PHY had distinct amyloid forming capabilities . Under artificially elevated concentrations of tetrafluoroethylene (TFE) and a short incubation time, PHY was able to form amyloid fibrils. These fibrils originating from tackynins like PHY were also shown to reduce the neurotoxicity of other Amyloid fibers associated with amyloid induced diseases such as Alzheimers disease. | 1 | Applied and Interdisciplinary Chemistry |
Genetic polymorphisms of genes that encode subunits of TFH are known to be associated with increased cancer susceptibility in many tissues, e.g.; skin tissue, breast tissue and lung tissue. Mutations in the subunits (such as XPD and XPB) can lead to a variety of diseases, including xeroderma pigmentosum (XP) or XP combined with Cockayne syndrome. In addition to genetic variations, virus-encoded proteins also target TFH. | 1 | Applied and Interdisciplinary Chemistry |
* 2016 Georges Guiochon Faculty Fellowship
* 2018 H. I. Romnes Faculty Fellowship
* 2019 Analytical Scientist Power List
* 2020 American Society for Mass Spectrometry Biemann Medal
* 2020 Analytical Scientist Power List
*2021 Human Proteome Organization (HUPO) Clinical and Translational Proteomics Award
*2021 Analytical Scientist Power List | 1 | Applied and Interdisciplinary Chemistry |
Microscopically the volume of a single pore in a porous media may be divided into two regions; surface area and bulk volume (Figure 1).
The surface area is a thin layer with thickness of a few molecules close to the pore wall surface. The bulk volume is the remaining part of the pore volume and usually dominates the overall pore volume. With respect to NMR excitations of nuclear states for hydrogen-containing molecules in these regions, different relaxation times for the induced excited energy states are expected. The relaxation time is significantly shorter for a molecule in the surface area, compared to a molecule in the bulk volume. This is an effect of paramagnetic centres in the pore wall surface that causes the relaxation time to be faster.
The inverse of the relaxation time , is expressed by contributions from the bulk volume , the surface area and the self-diffusion :
: with
where is the thickness of the surface area, is the surface area, is the pore volume, is the relaxation time in the bulk volume, is the relaxation time for the surface, is the gyromagnetic ratio, is the magnetic field gradient (assumed to be constant), is the time between echoes and is the self-diffusion coefficient of the fluid. The surface relaxation can be assumed as uniform or non-uniform.
The NMR signal intensity in the distribution plot reflected by the measured amplitude of the NMR signal is proportional to the total amount of hydrogen nuclei, while the relaxation time depends on the interaction between the nuclear spins and the surroundings. In a characteristic pore containing for an example, water, the bulk water exhibits a single exponential decay. The water close to the pore wall surface exhibits faster relaxation time for this characteristic pore size. | 0 | Theoretical and Fundamental Chemistry |
Konstantinos Drosatos (Greek: Κωνσταντίνος Δροσάτος), born in Athens, Greece, is a Greek-American molecular biologist, who is the Ohio Eminent Scholar and Professor of Pharmacology and Systems Physiology at the University of Cincinnati College of Medicine in Cincinnati, Ohio, U.S. His parents were Georgios Drosatos and Sofia Drosatou; his family originates in Partheni, Euboea, Greece. | 1 | Applied and Interdisciplinary Chemistry |
Some drugs enhance or inhibit the response to NMBAs which require the dosage adjustment guided by monitoring. | 1 | Applied and Interdisciplinary Chemistry |
* P. aeruginosa also uses 2-heptyl-3-hydroxy-4-quinolone (PQS) for quorum sensing. This molecule is noteworthy because it does not belong to the homoserine lactone class of autoinducers. PQS is believed to provide an additional regulatory link between the Las and Rhl circuits involved in virulence and infection.
* Agrobacterium tumefaciens is a plant pathogen that induces tumors on susceptible hosts. Infection by A. tumefaciens involves the transfer of an oncogenic plasmid from the bacterium to the host cell nucleus, while quorum sensing controls the conjugal transfer of plasmids between bacteria. Conjugation, on the other hand, requires the HSL autoinducer, N-(3-oxooctanoyl)-homoserine lactone.
* Erwinia carotovora is another plant pathogen that causes soft-rot disease. These bacteria secrete cellulases and pectinases, which are enzymes that degrade plant cell walls. ExpI/ExpR are LuxI/LuxR homologs in E. carotovora believed to control secretion of these enzymes only when a high enough local cell density is achieved. The autoinducer involved in quorum sensing in E. carotovora is N-(3-oxohexanoyl)-L-homoserine lactone. | 1 | Applied and Interdisciplinary Chemistry |
Thiones are usually prepared from ketones using reagents that exchange S and O atoms. A common reagent is phosphorus pentasulfide and the related reagent Lawesson's reagent. Other methods uses a mixture of hydrogen chloride combined with hydrogen sulfide. Bis(trimethylsilyl)sulfide has also been employed.
Thiobenzophenone [(CH)CS] is a stable deep blue compound that dissolves readily in organic solvents. It photooxidizes in air to benzophenone and sulfur. Since its discovery, a variety of related thiones have been prepared. | 0 | Theoretical and Fundamental Chemistry |
Engineering diffraction refers to a sub-field of neutron scattering which investigates microstructural features that influence the mechanical properties of materials. These include:
#lattice strain, a measure of distortion in crystals
#texture, a measure of grain orientations
#dislocation density, a measure of the microstructure
#grain morphology | 0 | Theoretical and Fundamental Chemistry |
The flow velocity u of a fluid is a vector field
which gives the velocity of an element of fluid at a position and time
The flow speed q is the length of the flow velocity vector
and is a scalar field. | 1 | Applied and Interdisciplinary Chemistry |
Biological photovoltaic systems are defined by the type of light harvesting material that they employ, and the mode of electron transfer from the biological material to the anode. | 0 | Theoretical and Fundamental Chemistry |
Two or more equilibria can exist at the same time. When this is so, equilibrium constants can be ascribed to individual equilibria, but they are not always unique. For example, three equilibrium constants can be defined for a dibasic acid, HA.
:A + H HA;
:HA + H HA;
:A + 2 H HA;
The three constants are not independent of each other and it is easy to see that . The constants K and K are stepwise constants and β is an example of an overall constant. | 0 | Theoretical and Fundamental Chemistry |
The first activation of a main group compound by yellow arsenic was reported in 1992 by West and coworkers, involving the reaction of As with a disilene compound, tetramesityldisilene, to generate a mixture of compounds including a butterfly structural motif of bridging arsenic atoms. Notably, the product mixture obtained in this reaction differs from the analogous reaction with P that produces the butterfly compound alone, highlighting that the reactivity of yellow arsenic and white phosphorus cannot be considered identical. The first organo-substituted As compound was produced by Scheer and coworkers in 2016 via reaction with the Cp radical. Analogous to the butterfly compound obtained by the West group, the product obtained in this reaction featured a bridging As motif that reversibly returned As and the parent radical in the presence of light or heat. This characteristic makes the CpAs complex a uniquely suitable "storage" molecule for yellow arsenic, as it is stable when stored at room temperature in the dark, but can release As in thermal or photochemical solutions.
Other reactions of main group compounds with yellow arsenic have been shown to involve units of arsenic with more than four atoms. In reaction with the silylene compound [PhC(NtBu)SiN(SiMe)], an aggregation of As was observed to form a cage compound of ten arsenic atoms, including a seven-membered arsenic ring at its center. | 0 | Theoretical and Fundamental Chemistry |
Long chain fatty acid uptake is mediated by several transporters, including FAT (fatty acid translocase)/CD36. CD36 deletion rescues lipotoxic cardiomyopathy. FAT/CD36 may be controlled by insulin and AMPK. Increased transport coupled to the formation of the CoA derivatives and the resulting AMPK activation should ensure efficient fatty acid uptake and metabolism. | 1 | Applied and Interdisciplinary Chemistry |
The world's first iron pillar was the Iron pillar of Delhi—erected at the times of Chandragupta II Vikramaditya (375–413), often considered as one of the finest pieces of ancient metallurgy. The swords manufactured in Indian workshops find written mention in the works of Muhammad al-Idrisi (flourished 1154). Indian Blades made of Damascus steel found their way into Persia. European scholars—during the 14th century—studied Indian casting and metallurgy technology.
Indian metallurgy under the Mughal emperor Akbar (reign: 1556–1605) produced excellent small firearms. Gommans (2002) holds that Mughal handguns were probably stronger and more accurate than their European counterparts.
Srivastava & Alam (2008) comment on Indian coinage of the Mughal Empire (established: April 21, 1526 - ended: September 21, 1857) during Akbar's regime:
Statues of Nataraja and Vishnu were cast during the reign of the imperial Chola dynasty (200–1279) in the 9th century. The casting could involve a mixture of five metals: copper, zinc, tin, gold, and silver.
Considered great feat in metallurgy, the hollow, Seamless, celestial globe was invented in Kashmir by Ali Kashmiri ibn Luqman in 998 AH (1589-90 CE), and twenty other such globes were later produced in Lahore and Kashmir during the Mughal Empire. These Indian metallurgists pioneered the method of lost-wax casting, and disguised plugs, in order to produce these globes. | 1 | Applied and Interdisciplinary Chemistry |
Wood dust is known to be a human carcinogen, based on sufficient evidence of carcinogenicity from studies in humans. It has been demonstrated through human epidemiologic studies that exposure to wood dust increases the occurrence of cancer of the nose (nasal cavities and paranasal sinuses). An association of wood dust exposure and cancers of the nose has been observed in numerous case reports, cohort studies, and case control studies specifically addressing nasal cancer. | 1 | Applied and Interdisciplinary Chemistry |
The identity of the inverting atom has a dominating influence on the barrier. Inversion of ammonia is rapid at room temperature, inverting 30 billion times per second. Three factors contribute to the rapidity of the inversion: a low energy barrier (24.2 kJ/mol; 5.8 kcal/mol), a narrow barrier width (distance between geometries), and the low mass of hydrogen atoms, which combine to give a further 80-fold rate enhancement due to quantum tunnelling. In contrast, phosphine (PH) inverts very slowly at room temperature (energy barrier: 132 kJ/mol). Consequently, amines of the type RR′R"N usually are not optically stable (enantiomers racemize rapidly at room temperature), but P-chiral phosphines are. Appropriately substituted sulfonium salts, sulfoxides, arsines, etc. are also optically stable near room temperature. Steric effects can also influence the barrier. | 0 | Theoretical and Fundamental Chemistry |
Several manufacturers produce EDM machines for the specific purpose of removing broken cutting tools and fasteners from work pieces. In this application, the process is termed "metal disintegration machining" or MDM. The metal disintegration process removes only the center of the broken tool or fastener, leaving the hole intact and allowing a ruined part to be reclaimed. | 1 | Applied and Interdisciplinary Chemistry |
The diffuse series used to be called the first subordinate series, with the sharp series being the second subordinate, both being subordinate to (less intense than) the principal series. | 0 | Theoretical and Fundamental Chemistry |
Native gels, also known as non-denaturing gels, analyze proteins that are still in their folded state. Thus, the electrophoretic mobility depends not only on the charge-to-mass ratio, but also on the physical shape and size of the protein. | 1 | Applied and Interdisciplinary Chemistry |
Phosphates are the naturally occurring form of the element phosphorus, found in many phosphate minerals. In mineralogy and geology, phosphate refers to a rock or ore containing phosphate ions. Inorganic phosphates are mined to obtain phosphorus for use in agriculture and industry.
The largest global producer and exporter of phosphates is Morocco. Within North America, the largest deposits lie in the Bone Valley region of central Florida, the Soda Springs region of southeastern Idaho, and the coast of North Carolina. Smaller deposits are located in Montana, Tennessee, Georgia, and South Carolina. The small island nation of Nauru and its neighbor Banaba Island, which used to have massive phosphate deposits of the best quality, have been mined excessively. Rock phosphate can also be found in Egypt, Israel, Palestine, Western Sahara, Navassa Island, Tunisia, Togo, and Jordan, countries that have large phosphate-mining industries.
Phosphorite mines are primarily found in:
* North America: United States, especially Florida, with lesser deposits in North Carolina, Idaho, and Tennessee
* Africa: Morocco, Algeria, Egypt, Niger, Senegal, Togo, Tunisia, Mauritania
* Middle East: Saudi Arabia, Jordan, Israel, Syria, Iran and Iraq, at the town of Akashat, near the Jordanian border.
* Central Asia: Kazakhstan
* Oceania: Australia, Makatea, Nauru, and Banaba Island
In 2007, at the current rate of consumption, the supply of phosphorus was estimated to run out in 345 years. However, some scientists thought that a "peak phosphorus" would occur in 30 years and Dana Cordell from Institute for Sustainable Futures said -ton crust, albeit at predominantly lower concentration than the deposits counted as reserves, which are inventoried and cheaper to extract. If it is assumed that the phosphate minerals in phosphate rock are mainly hydroxyapatite and fluoroapatite, phosphate minerals contain roughly 18.5% phosphorus by weight. If phosphate rock contains around 20% of these minerals, the average phosphate rock has roughly 3.7% phosphorus by weight.
Some phosphate rock deposits, such as Mulberry in Florida, are notable for their inclusion of significant quantities of radioactive uranium isotopes. This is a concern because radioactivity can be released into surface waters from application of the resulting phosphate fertilizer.
In December 2012, Cominco Resources announced an updated JORC compliant resource of their Hinda project in Congo-Brazzaville of 531 million tons, making it the largest measured and indicated phosphate deposit in the world.
Around 2018, Norway discovered phosphate deposits almost equal to those in the rest of Earth combined.
In July 2022 China announced quotas on phosphate exportation.
The largest importers in millions of metric tons of phosphate are Brazil 3.2, India 2.9 and the USA 1.6. | 0 | Theoretical and Fundamental Chemistry |
This table lists the gas–liquid–solid triple points of several substances. Unless otherwise noted, the data come from the U.S. National Bureau of Standards (now NIST, National Institute of Standards and Technology).
Notes:
* For comparison, typical atmospheric pressure is 101.325 kPa (1 atm).
* Before the new definition of SI units, water's triple point, 273.16 K, was an exact number. | 0 | Theoretical and Fundamental Chemistry |
The Abel test is a method developed by the British chemist Frederick Abel (1827–1902) to determine the flash point of a given sample of petroleum in order to ascertain the temperature at which it could safely be stored or used.
The test was mandated by the British Petroleum Act 1879, which fixed the minimum flash point for general and commercial use at . | 0 | Theoretical and Fundamental Chemistry |
Wetlands are sources of extreme biodiversity and ecological benefit. They contain a multitude of species of plants and animals, including 79 species classified as rare, threatened, or endangered. An estimate by the U.S. Fish and Wildlife Service indicates that wetlands provide for, directly and indirectly, up to 43% of federally threatened or endangered species. Wetlands are the leading producer of oysters, 50% of the shrimp crop, 75% of the alligator harvest, 27% of the oil and gas, and the largest port complex in the United States. The world’s wetlands have an estimated worth of $14.9 trillion.
Wetlands also provide for disaster protection, including surge protection from hurricanes, as they and barrier islands help to break down the power of a storm before it reaches mainland. They also provide flood relief, as they are able to hold about three-acre feet (one million gallons) of water. This holding of water allows for rejuvenation of ecosystems, as new sediment is able to settle. Flooding also affects factors such as root penetration, soil temperature, conductivity, and bulk density.
Wetlands are highly effective at removing pollutants and excess nutrients due to the slow water flow and absorption by the plant systems. This has been shown to be effective in the removal of nitrogen and phosphorus, the major nutrients involved in “dead zones”. They are also major sinks for heavy metals and sulfur. | 0 | Theoretical and Fundamental Chemistry |
Lyotropic liquid crystals result when amphiphiles, which are both hydrophobic and hydrophilic, dissolve into a solution that behaves both like a liquid and a solid crystal. This liquid crystalline mesophase includes everyday mixtures like soap and water.
To break the word down, "lyo" and "tropic" mean, respectively, "dissolve" and "change." Historically, the term was used to describe the common behavior of materials composed of amphiphilic molecules upon the addition of a solvent. Such molecules comprise a water-loving hydrophilic head-group (which may be ionic or non-ionic) attached to a water-hating, hydrophobic group.
The micro-phase segregation of two incompatible components on a nanometer scale results in different type of solvent-induced extended anisotropic arrangement, depending on the volume balances between the hydrophilic part and hydrophobic part. In turn, they generate the long-range order of the phases, with the solvent molecules filling the space around the compounds to provide fluidity to the system.
In contrast to thermotropic liquid crystals, lyotropic liquid crystals have therefore an additional degree of freedom, that is the concentration that enables them to induce a variety of different phases. As the concentration of amphiphilic molecules is increased, several different type of lyotropic liquid crystal structures occur in solution. Each of these different types has a different extent of molecular ordering within the solvent matrix, from spherical micelles to larger cylinders, aligned cylinders and even bilayered and multiwalled aggregates. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, isothiocyanate is a functional group as found in compounds with the formula . Isothiocyanates are the more common isomers of thiocyanates, which have the formula . | 0 | Theoretical and Fundamental Chemistry |
Metabonomics is defined as "the quantitative measurement of the dynamic multiparametric metabolic response of living systems to pathophysiological stimuli or genetic modification". The word origin is from the Greek μεταβολή meaning change and nomos meaning a rule set or set of laws. This approach was pioneered by Jeremy Nicholson at Murdoch University and has been used in toxicology, disease diagnosis and a number of other fields. Historically, the metabonomics approach was one of the first methods to apply the scope of systems biology to studies of metabolism.
There has been some disagreement over the exact differences between metabolomics and metabonomics. The difference between the two terms is not related to choice of analytical platform: although metabonomics is more associated with NMR spectroscopy and metabolomics with mass spectrometry-based techniques, this is simply because of usages amongst different groups that have popularized the different terms. While there is still no absolute agreement, there is a growing consensus that metabolomics places a greater emphasis on metabolic profiling at a cellular or organ level and is primarily concerned with normal endogenous metabolism. Metabonomics extends metabolic profiling to include information about perturbations of metabolism caused by environmental factors (including diet and toxins), disease processes, and the involvement of extragenomic influences, such as gut microflora. This is not a trivial difference; metabolomic studies should, by definition, exclude metabolic contributions from extragenomic sources, because these are external to the system being studied. However, in practice, within the field of human disease research there is still a large degree of overlap in the way both terms are used, and they are often in effect synonymous. | 1 | Applied and Interdisciplinary Chemistry |
This section is about frequency dispersion for waves on a fluid layer forced by gravity, and according to linear theory. For surface tension effects on frequency dispersion, see surface tension effects in Airy wave theory and capillary wave. | 1 | Applied and Interdisciplinary Chemistry |
Magnetoelectrochemistry is a branch of electrochemistry dealing with magnetic effects in electrochemistry. | 0 | Theoretical and Fundamental Chemistry |
There are two Dutch assay offices located in the city of Gouda and Joure. The Dutch recognize platinum, gold, silver and palladium as precious metals. | 0 | Theoretical and Fundamental Chemistry |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.